/Engine/Source/Runtime/Core/Public/GenericPlatform/GenericPlatformProcess.h
Launch a uniform resource locator (i.e.http://www.epicgames.com/unreal). This is expected to return immediately as the URL is launched by another task. The URL param must already be a valid URL. If you're looking for code to properly escape a URL fragment, useFGenericPlatformHttp::UrlEncode.
static void LaunchURL ( const TCHAR * URL, const TCHAR * Parms, [FString](API\Runtime\Core\Containers\FString) * Error )